The anaerobic corrosion of carbon steel in saturated compacted bentonite in the Swiss repository concept

Abstract

Carbon steel is a candidate disposal canister material for high-level radioactive waste and spent fuel in the Swiss deep geological repository concept and so a long-term laboratory-based corrosion experiment was undertaken to measure the anaerobic corrosion behaviour and corrosion rate of carbon steel in compacted bentonite under simulated anoxic repository conditions. The corrosion rate was measured using barometric gas cells over a period of more than 5 years, until quasi-steady-state conditions were reached. The measured corrosion rates are in agreement with weight loss measurements and with previous tests under similar conditions. The carbon steel and surrounding bentonite removed from one cell after 3 years were analysed with a range of analytical techniques, weight loss measurements and mineralogical characterisation. The results provide an insight into the prevailing corrosion mechanisms under repository conditions.This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.